In an internal combustion engine system having dedicated EGR (exhaust gas recirculation), one or more cylinders of the engine are segregated and dedicated to operate in a rich combustion mode. As a result of the rich combustion, the exhaust gases from the dedicated cylinder(s) include hydrogen and carbon monoxide. Rich combustion products such as these are often termed “syngas”.
Dedicated EGR engines use the syngas produced by the dedicated cylinder(s) in an exhaust gas recirculation (EGR) system. The hydrogen-rich syngas is ingested into the engine for subsequent combustion by the non-dedicated cylinders and optionally by the dedicated cylinder(s). Benefits of combustion with dedicated EGR are numerous, but include engine efficiency improvements and emissions improvements (reduction of NOx, carbon monoxide and particulate matter).
Dedicated EGR has been successfully used with engines that operate with stoichiometric combustion in the non-dedicated cylinders, whose exhaust exits into the exhaust treatment system of the engine. The stoichiometric exhaust allows very effective use of traditional three-way catalyst technology for emissions reductions.